Assessing the effects of atmospheric nitrogen (N) deposition on surface water quality requires accurate accounts of total N deposition (wet, dry, and cloud vapor); however, dry deposition is difficult to measure and is often spatially variable. Affordable passive sampling methods are available for estimating “hot spots” and spatial variations of gaseous dry N deposition (i.e., nitrogen dioxide (NO2) and ammonia (NH3)), though few viable methods for estimating the deposition from nitric acid (HNO3) gas using passive sampling techniques exist. We consider passive sampling approaches for assessing spatial patterns of dry atmospheric N deposition across watersheds. We describe a method for constructing an inexpensive passive sampler (for less than $12 per unit) for monitoring spatial variations in the magnitude of HNO3 in the atmosphere. We demonstrate the applicability of passive samplers for use in watershed biogeochemical research and water quality management through a review of previous applications and via our own case study of the South Korean peninsula.